Electrical connector



Oct. 6, 1942. W RQSE ET AL 2,298,172

Y ELECTRICAL CONNECTOR V im? Filed March 21. 1941 is' ik INVENTORS .L50 14./ R055 Jof//v C. L/NDBEKG .fof/NI MoFF/Tr ATTORNEYS 4Patented Oct. 6, 1942 UNITED STATES PATENT OFFICE ELECTRICAL CONNECTOR Leo W. Rose and John C. Lindberg, Dover, and John J. Monitt, New Philadelphia, Ohio Application March 21, 1941, Serial No. 384,430

, 3 Claims.

This invention relates to electrical connector construction, and more especially it relates to improved electrical connectors of the plug and socket type. 'I'he application is a substitute in part for our prior application Serial No. 231,942, filed September 27, 1938.

The invention is of primary utility as a service outlet for lamp cords, and the cords of other portable electrical .household appliances, but itis capable also of advantageous use for the mounting of incandescent lamp bulbs, and fuses.

The chief objects of the invention are to provide an improved electrical connector of the push-in type that Will aiord effective and positive connection of the electrical contact elements; that will provide a rigid connection between the interengaged elements; that does not require the respective parts thereof to be in any determinate angular relationship in order to make electrical connection; and to provide a connector of the character mentioned that is not a source of danger to infants or others who might insert ngers thereinto. More specically the invention aims to provide an electrical connection such that the plug portion thereof is easily and readily tted into the socket portion thereof while the plug portion is held in any angular relation to the socket portion, whereby a saving of time and eiort is achieved. ther objects will be manifest as the description proceeds.

Of the accompanying drawing:

Figure 1 is a section through an embodiment of the invention as it applies to a socket and a plug on the end of a conductor cord, said section being taken on the line I-I of Fig. 2;

Figure 2 is a bottom plan view of the structure shown in Fig. 1, an escutcheon plate being omitted;

Figure 3 is a fragmentary elevation of the base portion of an electric lamp bulb adapted to be mounted in a socket structure such as that shown in Figs. 1 and 2; and

Figure 4 is a diametric section-through a fuse plug that is mountable in the socket structure shown.

Referring particularly to Figures 1 and 2 of the drawing, it will be seen that the connector consists of ka female member or socketv portion, and a male member receivable therein, in this instance the male member being a plug on one end of a conductor cord. The female portion comprises the usual molded body structure I0 composed of dielectric material such as porcelain, hard rubber or other suitable plastic such as Bakelite. The structure I0 as shown is of oblong 55 receptacle.

The body structure I0 is formed in its rear or shape, and includes two plug-receiving sockets, but other shapes may be employed if desired and diierent numbers of plug-receiving sockets may be provided. The structure IIJ is designed to 'be mounted in the usual metal boX-like-receptacle (not shown) that usually is inset in a wall, and apertured ears II, II project from opposite ends of the structure for securing the same in said cess I6, each of the latter is formed with a frustoconical surface Il that diverges from said juncture. Mounted within each recess IB is an annular electrical contact member or shell I8 that is made of brass or other suitable electrically conductive sheet metal of a springy nature. Each. conductor shell I8 has a frusto-conical end portion that seats snugly within the frustoconical portion Il of recess I6, and struck out from the side of each shell I8 at three symmetrically disposed points are apertured ears I9, I9 thatl bear against an annular shelf or ledge 20 in each recess I 6. Each shell I8 is retained in the recess I6 by means of screws that extend through the respective ears I9 and are threaded into one of 'a pair of arcuate metal conductor plates 2l that are molded into the body structure II), concentrically of the annular recesses I6 and ilush with the top of the respective ledges 20 thereof. Each contact plate ZI has a portion 22 that is disposed at right angles thereto and extends therefrom toward the rear or bottom of the structure I, the terminal portion of member 22 being bent at right angles parallel to plate 2 I, and disposed in a recess 23 in the rear face of the structure, said recesses 23 being disposed at opposite ends of the recess I4 and opening lat.

erally into the latter. Also mounted in' each re- .cess 23 is a contact plate 24 that is secured to the terminal portion of member 22 therein by means of a screw 25, the plates 24 extending into recess I4, and preferably being slightly bent, at an angle to the plane of recess I4, for a purpose presently to be explained. Each plate 24 lits snugly Within its recess 23 so as always to maintain the same angular position therein, the free end of each plate being disposed substantially opposite one of the apertures I5 of the body structure, but in spaced relation thereto.

Each conductor shell I8 is of general frustoi conical shape, its larger end portion being axially cut or slit at a plurality of spaced points circumferentially of the shell, as shown at 21, 21. At a region relatively near the larger end of the shell, the latter is formed with a constricted region defined by an annular, inwardly-extending rib 28 that is angular in section. On the exterior of the shell the rib 28 defines a groove, Land received in said groove is an endless coiled tension spring 23, the function of which is yieldingly to resist the spreading of the slitted end portion of the shell under the pressure of a male or plug portion of the connector, when said plug portion is inserted in the shell, and to assist in retaining said male or plug portion in place after it is seated therein. If desired, a relatively stiff, split ring of wire may be used in place of the spring 28 for exerting a constrictive force upon the slitted portion of the shell I8. The usual escutcheon plate 30 of metal or molded material is mounted over the body structure I when the iatter is installed for use, and retained thereon by a screw 3I that is threaded into a metal plate 32 that is molded into said body structure. 'I'he escutcheon plate is formed with a pair of apertures 33, 33 that give access to the respective conductor shells I8.

The male or plug portion of the connector comprises two major portions designated 35 and- 38,-both of which are composed of dielectric material. Portion 35 is of general frusta-conical shape designed to be received within either conductor shell I8, the smaller end or-nose of the structure having an integral axial pilot or extension 35a of cylindrical shape that is receivable in the apertures I5 of the body structure I0 with an easy sliding fit. Adjacent the larger end of the plug portion 35 is an annular groove 31 of. angular cross section in which the rib 23 of a conductor shell I8 will seat when the plug structure is inserted therein. 'An annular metal contact ring 38 that is angular in section is molded onto the plug 35, circumferentially thereof, one leg of ring l38 constituting a side of groove 31, the other leg of the ring being disposed substantially flush with the tapered portion of the plug between groove 31 and extension 35a. The arrangement is such that ring 38 will make electrical contact with conductor shell I8 when the plug is mounted in said shell. A conductor wire 33 molded into the plug structure 35 connects contact ring 38 with a terminal plate 48 molded into the plane face of the plug at the large end thereof. A screw 4I is threaded into plate 40 for the purpose of connecting one conductor wire 42 of a duplex conductor cord 43 thereto.

Molded into the end face of extension 35a of plug 35 is a metal contact member 45 adapted to make electrical contact with a spring contact member (presently to be described) when the plug-is inserted in a female portion of the connector. A conductor wire 48 is molded into the plug structure and connects contact member 45 with a terminal plate 41 molded into the plane' face of the plug, at l*a point diametricallyopposite the plate 48 therein. A screw 48 is threaded into plat 41 for the purpose of connecting the other conductor wire 48 of the cord 43 thereto,

Portion 38 of the male element is a hand-grip structure or knob for the convenient manipulation of plug portion 35. Portion 38 is transversely circular, and is formed` with an axial aperesI ture 5| to enable the cord 43 to pass therethrough. A The portion 38 is secured to the large end of plug portion 35, in axial alignment therewith, by means of a pair of screws. such as the screw 52, that extend through suitable holes in said portion 38 and are threaded into respective metal inserts, such as the insert 53, Fig. l, that are molded into the plane face of structure 35 at dlametrically opposite points, and offset from the terminal plates 40, 41 therein. The under side of structure 38 is recessed at 54 to provide clearance for the screws 4I and 48 and the conductor wires 42 and 43 connected thereto.

Positioned on each side of the body structure I3, centrally thereof, are respective terminal plates 58, 51, said plates being angular in shape. The

plates 58, 51 are molded into the body strucv ture I3, the arrangement being such that one leg of each is exposed upon a lateral face of the body structure. the other leg of each extending through the wall of the body structure and into the recess I4 in the rear face thereof. said plates being flush with the bottom of said recess and at opposite sides thereof. Mounted .in the recess I4 are spring contact elements 58 and 53. and a thin, exible sheet 88 of dielectric material such as hard rubber disposed between them and insulating them one from the other. Each contact element 58 and 53 is in the form of a one-piece structure consisting of a pair of springs that are disposed at an obtuse angle to each other, the obtuse angles of the two elements being in confronting relation and the respective spring ends of one element crossing the spring ends of the other element. The arrangement is such that the crossed spring ends are disposed opposite the respective apertures I5 of the body structure I3, between the latter and the respective contact plates 24. The medial regions of the contact elements 58, 53 overlie the terminal plates 58, 51 respectively and are secured to the same by screws 6I, 6I that also extend through the interposed insulating sheet 88 to retain the latter in place. The medial region of each contact element 58, 53 has an oifset portion that bears ilush against the marginal wall of the recess I4 whereby swivelling of the respective contact elements about their mounting screws 8| is prevented. The spring assembly described readily is mounted within the recess I4 before the contact plates 24 are secured in place. Electrical conductor wires 53, 63 from any convenient source of electric current are connected to the terminal plates 58, 51 in the usual manner by screws 84, 84.

'I'he plug element of the connector is operatively associated with'either of the socket or female elements thereof simply by pushing it thereinto until the contact ring 38 of the plug passes the inwardly extending rib 28 of the socket, as shown in the right-hand portion of Figure l. During this operation the slitted portion of the shell I8 spreads, against the tension of spring 23. Thereafter the spring retains the shell in close contact with the ring 38 whereby good elecwith an axially. disposed recess 1I in its-outer with, and the seating of the plug-extension 35a in the body aperture I5 makes for rigidity of the assembled connector so that the plug member will not accidentally be jarred loose from the socket. In the insertion of the plug into a socket, there is friction between the contactring 38 and the rib 28, but since both parts are of metal, they will have relatively long life notwithstanding such friction. Should the shell I8 become worn or damaged it may be replaced readily since the'screws that support it are accessible from the front of the connector.

It will be noted with relation to the left hand socket shown in Fig. l that the contact spring 58 is out of contact with adjacent contact plate 24 with the result that shell I8 has no connection with a source of electrical energy, and it constitutes no hazard to children who might insert a finger into the socket. As previously stated, the aperture I5 is too small to admit a human finger, so that the contact spring 59 presents no hazard. When a plug is-fully seated in a socket, as shown in the right hand portion of Fig. 1, the extension 35a of the plug extends through aperture I5 of the body structure I0,

- the metal contact member on the end of said extension engaging the end of contact spring 59 opposite said aperture, and flexing said spring 59, and insulator 68 and companion spring 58,

4so that the latter spring makes contact with the adjacent plate 24. Thus the shell I8 is energized end, in which recess is positioned a strip of fuse metal 'I2 connected .at its opposite ends to respective conductor wires 13, 14 that extend to the electrical contact elements 15, 18 of the plug. The recess 1I is overlaid with a transparent disc 11 that is retained on the end of the plug by an apertured metal cap 18, the latter having its marginal portion crimped around a circumferential flange 18a on the end of the plug structure.

Other modification may be resorted to without departing from the spirit of the invention, or the scope thereof as defined by the appended claims.

What is claimed is:

1. An electrical connector comprising a male and a female element, said female element comprising a metal contact shell of frusto-conical shape that is open at bothv ends, and formed adjacent its larger end with an inwardly extending circumferential rib, the larger end portion of the shell being axially slit at a. plurality of points, means circumscribing the slitted portion of the shell yieldingly opposing distensionA thereof, a pair of normally energized electrical con` tact springs disposed beyond the opening at the smaller end of the shell, said opening vbeing too through the agency of connections 22, 2I, and

I9 and current is enabled to flow through both conductors of the cord 43. The slightly angular shape of the contact plates 24 enables the springs 58 to make contact therewith over a substantial area, thereby avoiding high resistance in the connection.

Although the male and female elements of the connector are shown as comprising frustoconical portions, it is not desired that they be limited to this particular shape since other shapes, for example, cylindrical shape or hemispherical shape may be employed without .material sacrice of the advantageous features of the invention. The improved connector is easy y to operate under all conditions, it is safe in that it presents no danger to infants or`others who may carelessly insert' fingers therein, and it achieves the other advantages set out in the foregoing statement of objects.

Referring now to Fig. 3 of the drawing, there is shown an incandescent lamp bulb having a base portion 66 that is essentially similar to the plug 35 hereinbefore described in external configuration, said base being receivable in a socket structure that is identical with that described. The base 56 differs from the plug 35 in that its terminal contact element 61 and its circumferential contact ring 68 are connected to the lighting filament of the lamp'bulb in the usual manner as will be understood. The arrangement is such that the lamp bulb may be mounted in a socket simply by pushing it thereinto, no turning or twisting of the bulb being required. The bulb is securely held in place,

` and cannot be jarred loose so as to separate the y and 2 of the drawing. In this embodiment of the invention, the plug structure 1I) is formed small to receive a human finger and an electrical contact member connected to said shell and extending to a point adjacent one of said contact springs, said male element comprising a frustoconical plug of dielectric material receivable in said shell and formed with a circumferential groove in which the rib of the shell is engageable, a metal contact ring about the said plug adapted 'to make electrical contact with the metal of the shell, anda metal contact member on the small end of the' plug adapted to engage one of the contact springs of the female element and make electrical contact therewith through the open small end of the shell, and to vforce the other contact spring of the female element into contact with the contact member that is connected to the shell.

2. An electric connector comprising a male and a female element, said female element com prlsing a body structure of dielectric material formed with a cylindrical aperture at one side thereof opening into a recess of irregular shape in the opposite-side thereof, said aperture being too small to receive a human finger, the latter recess having a frusto-conical region at its juncture with said cylindrical aperture, a metal contact shell of frusta-conical shape that is open at both ends mounted in said body with its smaller end` portion seated upon the frustoconial surface of the said recess therein and having a distensible constricted region adjacent its larger end, and an electrical contact spring disposed -adjacent the outer end of the cylindrical aperture in the body and remote froml the end of said shell, said male element comprising a frusto-conical plug of dielectric material seat-v able in said contact shell and formed with a cylindrical extension on its smaller end of a size small enough to be receivable in the cylindrical aperture of said body, a circumferentially extending electrical contact member on the frustoconical portion of the vplug adapted for electrical contact with saidshell, and adaptedmechanically to interlock with the constricted portion of the shell when plug and shell are moved.'

together non-rotatably in an axial direction,

said cylindrical extension for electrical contact with the contact spring at the outer end. of the cylindrical aperture in said body.

l3. An electrical connector comprising a male and a female element, said female element comprising a body structure of dielectric material that is formedwith a cylindrical aperture at one side thereof opening into a recess of irregular' shape on the opposite side thereof, said aperture being of such small size as not to admit a human nger thereinto, the said recess having a frustoment comprising a i'rusto-conical plug of dielectric material seatable in said contact shell and formed with a cylindrical axial extension on its smaller end of a size small enough to be slidably received in the cylindrical aperture of said body, an electrical contact member consisting of a metal rib mounted on the frusta-conical portion of the plug adapted for electrical contact with the circumferential rib' on said shell. and an electrical contact member on the end of said cylindrical extension for electrical contact with the contact spring at the outer end of the cylindrical aperture of said body.

' LEO W. ROSE.

JOHN C. LINDBERG. JOHN J. MOFFI'I'I. 

